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IBM did research back in the 90s on perceptually-based colormaps and how to best represent various types of data within the color dimensions of luminescence, sa

IBM did research back in the 90s on perceptually-based colormaps and how to best represent various types of data within the color dimensions of luminescence, saturation and hue [1]. For exampale, they found that, (1) Hue was not a good dimension for encoding magnitude information, i.e. rainbow color maps are bad. (2) The mechanisms in human vision responsible for high spatial frequency information processing are luminance channels. If the data to be represented have high spatial frequency, use a color map which has a strong luminance variation across the data range. (3) For interval and ratio data, both luminance- and saturation-varying color maps should produce the effect of having equal steps in data value correspond to equal perceptual steps, but the first will be most effective for high spatial frequency data variations and the second will be most effective for low spatial frequency variations. === [1] https://www.research.ibm.com/people/l/lloydt/color/color.HTM https://www.research.ibm.com/people/l/lloydt/color/color.HTM or as pdf: https://github.com/frankMilde/interesting-reads/blob/master/ https://github.com/frankMilde/interesting-reads/blob/master/...

jrib 6y ago
For the pdf, did you mean to link to: https://github.com/frankMilde/interesting-reads/raw/master/ibm-research__why-should-engineers-and-scientists-be-worried-about-color.pdf https://github.com/frankMilde/interesting-reads/raw/master/i...
lelandbatey 6y ago
Your second link is somehow broken, I think it was truncated during copy-paste. Here's the PDF link: https://github.com/frankMilde/interesting-reads/blob/master/ibm-research__why-should-engineers-and-scientists-be-worried-about-color.pdf https://github.com/frankMilde/interesting-reads/blob/master/...
deleted 6y ago
[deleted]
thethirdone 6y ago
The first link doesn't seem to have any content and the second link should be https://github.com/frankMilde/interesting-reads/blob/master/ibm-research__why-should-engineers-and-scientists-be-worried-about-color.pdf https://github.com/frankMilde/interesting-reads/blob/master/... > (1) Hue was not a good dimension for encoding magnitude information, i.e. rainbow color maps are bad. Specifically the pdf claims that a naive rainbow color map is bad and references the work of S.S. Stevens for "hue was not a good dimension for encoding magnitude information"
tagh 6y ago
Here's a gallery [1] of perceptually uniform colour maps, both lightness-varying and isoluminant (the latter are particularly useful in conjuction with hillshade filters). The maps are present in many libraries / languages. === [1] https://www.colorcet.com/gallery.html https://www.colorcet.com/gallery.html
Pyrodogg 6y ago
I was just watching a seminar about color grading in portrait photography and it also talked about luminosity, how it's processed faster than color, and how to account for it while color grading. For artistic affect, it may be preferred to have near equal luminosity throughout the image so that the luminance variance doesn't allow you to "make up your mind" about the image before processing the color. Interesting to so soon come across related studies without searching.
- Hnrobert42 6y ago
  I am interested in what you are saying. If I can ask for a favor, could you maybe link to examples of two different portraits: one with uniform luminosity and one without? I don’t really know enough about color theory and the terminology to imagine what you are describing. I don’t even know enough to properly search for example images myself. Hence the request. :-)
  - Pyrodogg 6y ago
    Here's a link to the point in the video where this concept was discussed. It references two classical art paintings, and two photographs from the presenter. https://youtu.be/mC8ol2-V7Ck?t=2116 https://youtu.be/mC8ol2-V7Ck?t=2116
    - Hnrobert42 6y ago
      That’s awesome. Thank you!
- jacobolus 6y ago
  Nit: "luminosity" is an incorrect term to use here. https://en.wikipedia.org/wiki/Luminosity https://en.wikipedia.org/wiki/Luminosity You probably mean "lightness", but you might mean "luminance" or "brightness", depending on the details. https://en.wikipedia.org/wiki/Lightness https://en.wikipedia.org/wiki/Lightness https://en.wikipedia.org/wiki/Luminance https://en.wikipedia.org/wiki/Luminance
  - 6y ago

jrib 6y ago

For the pdf, did you mean to link to: https://github.com/frankMilde/interesting-reads/raw/master/ibm-research__why-should-engineers-and-scientists-be-worried-about-color.pdf https://github.com/frankMilde/interesting-reads/raw/master/i...

lelandbatey 6y ago

Your second link is somehow broken, I think it was truncated during copy-paste. Here's the PDF link: https://github.com/frankMilde/interesting-reads/blob/master/ibm-research__why-should-engineers-and-scientists-be-worried-about-color.pdf https://github.com/frankMilde/interesting-reads/blob/master/...

deleted 6y ago

[deleted]

thethirdone 6y ago

The first link doesn't seem to have any content and the second link should be https://github.com/frankMilde/interesting-reads/blob/master/ibm-research__why-should-engineers-and-scientists-be-worried-about-color.pdf https://github.com/frankMilde/interesting-reads/blob/master/... > (1) Hue was not a good dimension for encoding magnitude information, i.e. rainbow color maps are bad. Specifically the pdf claims that a naive rainbow color map is bad and references the work of S.S. Stevens for "hue was not a good dimension for encoding magnitude information"

tagh 6y ago

Here's a gallery [1] of perceptually uniform colour maps, both lightness-varying and isoluminant (the latter are particularly useful in conjuction with hillshade filters). The maps are present in many libraries / languages. === [1] https://www.colorcet.com/gallery.html https://www.colorcet.com/gallery.html

Pyrodogg 6y ago

I was just watching a seminar about color grading in portrait photography and it also talked about luminosity, how it's processed faster than color, and how to account for it while color grading. For artistic affect, it may be preferred to have near equal luminosity throughout the image so that the luminance variance doesn't allow you to "make up your mind" about the image before processing the color. Interesting to so soon come across related studies without searching.

Hnrobert42 6y ago
I am interested in what you are saying. If I can ask for a favor, could you maybe link to examples of two different portraits: one with uniform luminosity and one without? I don’t really know enough about color theory and the terminology to imagine what you are describing. I don’t even know enough to properly search for example images myself. Hence the request. :-)
- Pyrodogg 6y ago
  Here's a link to the point in the video where this concept was discussed. It references two classical art paintings, and two photographs from the presenter. https://youtu.be/mC8ol2-V7Ck?t=2116 https://youtu.be/mC8ol2-V7Ck?t=2116
  - Hnrobert42 6y ago
    That’s awesome. Thank you!
jacobolus 6y ago
Nit: "luminosity" is an incorrect term to use here. https://en.wikipedia.org/wiki/Luminosity https://en.wikipedia.org/wiki/Luminosity You probably mean "lightness", but you might mean "luminance" or "brightness", depending on the details. https://en.wikipedia.org/wiki/Lightness https://en.wikipedia.org/wiki/Lightness https://en.wikipedia.org/wiki/Luminance https://en.wikipedia.org/wiki/Luminance
- 6y ago